Polishing fluid and method of polishing

ABSTRACT

A polishing slurry comprises a metal-oxidizing agent, a metal anticorrosive agent, an oxidized metal dissolving agent and water. The oxidized metal dissolving agent is at least one kind selected from the group consisting of an acid in which the negative value of the logarithm of the dissociation constant Ka (pKa) of a first dissociable acid group is 3.5 or more, an ammonium salt of the acid and an organic acid ester of the acid. The pH of the polishing slurry is within the range of 3 to 4. The concentration of the metal-oxidizing agent is within the range of 0.01 to 3 percent by weight. In the wiring-formation process of the semiconductor device, the conductor used for the barrier layer can be polished at a high polishing rate by using the polishing slurry having the low polishing particle concentration and the low metal anticorrosive agent concentration.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing slurry, and particularly, apolishing slurry used for polishing in the wiring-formation process of asemiconductor device, and a polishing method using the polishing slurry.

2. Description of the Related Art

Recently, as a Large-Scale Integrated circuit (hereinafter, referred toas “LSI”) of a semiconductor advances to fulfil the demand of higherintegration and performance, new microprocessing techniques have beendeveloped. The Chemical Mechanical Polishing (hereinafter, referred toas “CMP”) method is one of the new microprocessing techniques, which isoften used in a LSI production process, especially for flatteninginterlaminar insulating films, formation of a metal plug and embeddedwires in a multi-layered wiring-formation process. This technique isdisclosed in U.S. Pat. No. 4,944,836.

Additionally, in recent years, use of copper and copper alloy as a wirematerial has been mainly attempted in order to enhance the performanceof LSI. However, in the case of the copper and the copper alloy, it isdifficult to perform microprocessing according to dry etching, which hasbeen often used in the conventional method for forming aluminum alloywiring. Therefore, there has been employed what is called Damascenemethod in which copper or a thin film of copper alloy is accumulated onand embedded in an insulating film by way of a groove formed in advanceon the insulating film and then the copper or the copper alloy thin filmremaining at the portions other than the groove portion is removed byCMP, whereby embedded wiring is formed. For instance, this technique isdisclosed in Japanese Patent Application Laid-Open (JP-A) No. 2-278822.

In general, a CMP method in metal processing such as copper and a copperalloy includes the steps of: sticking a polishing pad on a disc-shapedpolishing platen; soaking the surface of the polishing pad with apolishing liquid for metal; pressing, one surface of a substrate onwhich a metal film has been formed, against the surface of the polishingpad, with applying a predetermined pressure (hereinafter, referred to as“polishing pressure”) thereon from the back surface of the substrate,and rotating the polishing platen in that state; and removing theprojected portion of the metal film by utilizing mechanical frictionbetween the polishing liquid and the projected portion of the metalfilm.

The polishing liquid for metal used for CMP generally contains ametal-oxidizing agent and solid polishing particles. An oxidized metaldissolving agent and a metal anticorrosive agent are further addedthereto, according to necessity. With regards to the basic mechanism ofCMP, it is assumed that at first the surface of the metal film isoxidized by an oxidizing agent; and then the oxidized layer is scrapedoff by the solid polishing particles. The oxidized layer existing at thedented portion of the metal surface is hardly brought into contact withthe polishing pad and thus the solid polishing particles do not have somuch scraping effect thereon. In other words, the metal layer present atthe projected portion of the substrate surface is removed as CMP iseffected, whereby the substrate surface is made flat and smooth. Thedetails of the feature described above is disclosed in Journal ofElectrochemical Society, vol. 138, No. 11 (1991), pp. 3460-3464.

It has been known that addition of an oxidized metal dissolving agent iseffective as a method for increasing the polishing rate by CMP. It isunderstood that addition of an oxidized metal dissolving agent iseffective because the scraping effect by the solid polishing particlesis enhanced by dissolving (hereinafter, referred to as “etching”) theparticles of metal oxides, which have been scraped off by the solidpolishing particles, in the polishing liquid. The polishing rate due toCMP is increased by adding the oxidized metal dissolving agent. However,if the oxidized layer existing at the dented portion of the metal filmsurface is also etched and the metal film surface is exposed, the metalfilm surface is further oxidized by the oxidizing agent. In a case inwhich such excessive etching is repeated, the metal film at the dentedportion is considerably etched. Thereby, a phenomenon (hereinafter,referred to as “dishing”) is occurred in which the center portion at thesurface of the embedded metal wiring is recessed like a dish afterpolishing, and the flattening effect is damaged.

In order to prevent such excessive etching from being occurred, a metalanticorrosive agent for protecting the metal surface further is added.The metal anticorrosive agent forms a protective film on the oxidizedlayer of the metal film surface, and prevents the oxidized layer fromsolving in the polishing slurry. This protective film can be scraped offeasily by the solid polishing particles, and the polishing rate due toCMP is preferably maintained.

In order to suppress dishing and etching of copper and copper alloyduring polishing and form highly reliable LSI wiring, there has beenproposed a method for using a polishing liquid for metal containing: anoxidized metal dissolving agent composed of an amino acetic acid (suchas glycine) or amido sulfuric acid; and BTA (benzotriazol) as the metalanticorrosive agent. This technique is disclosed, for example, in JP-ANo. 8-83780.

In the Damascene wiring formation of copper or copper alloy or themetal-embedding formation such as plug wiring formation of tungsten orthe like, if the polishing rate of the silicon dioxide film as theinterlaminar insulating film formed at the portion other than theembedded portion is also large, there arises the phenomenon of“thinning” in which reduction of wiring thickness and reduction ofthickness of the interlaminar insulating film simultaneously occur. As aresult, since there is generated variation in resistance due to theincrease in the wiring resistance, the pattern density or the like, acharacteristic that the polishing rate of the silicon dioxide film issufficiently smaller than that of the metal film to be polished isrequired. Therefore, there has been proposed a method in which pH of thepolishing liquid is made higher than the negative value of the logarithmof the dissociation constant Ka (pKa) of the first dissociable acidgroup of an oxidized metal dissolving agent −0.5 by suppressing thepolishing rate of silicon dioxide by the action of an anion produced asa result of dissociation of an acid. This technique is disclosed, forexample, in Japanese Patent No.2819196.

As a lower layer beneath metal for wiring portion such as copper orcopper alloy, a barrier layer of a conductor selected from the group,for example, consisting of tantalum, tantalum alloy, tantalum nitrideand tantalum compounds of other types (hereinafter, referred to as“tantalums”) is formed in order to prevent copper from diffusing intothe interlaminar insulating film and enhance the adhesion. Accordingly,at the portion other than the wiring portion at which copper or copperalloy is to be embedded, the exposed barrier layer must be removed byCMP. However, as the barrier layer conductor is harder than copper orcopper alloy, a sufficiently high polishing rate is hardly obtained andflatness often worsens, even if a combination of the polishing materialsfor copper or copper alloy is simply employed. Therefore, there has beenstudied a two-stage polishing method including the first step ofpolishing metal for wiring portion and the second step of polishing thebarrier layer conductor.

The conductors generally used as the barrier layer, for example, theabove tantalums, titanium and the compound thereof, tungsten and thecompound thereof or the like are chemically stable. In addition theetching of the conductors is difficult, and the conductors have highhardness. Thereby, the mechanical polishing thereof is not so easy asthat of copper and a copper alloy. When the hardness of the polishingparticles is increased, polishing crack is occurred on copper or copperalloy, and the poor electrical property is caused. When the particleconcentration of the polishing particles is increased, a problem existsin that the polishing rate of a silicon dioxide film becomes faster, andthinning is occurred.

It has been considered that in CMP of the barrier layer as the secondprocess, the dishing in the embedding wiring portion of copper or copperalloy must be prevented and the low pH of the polishing slurry is minuseffect so as to suppress the polishing rate and etching rate of copperor copper alloy. On the other hand, as the polishing slurry which iseffective for polishing the barrier layer, the following polishingslurry is proposed. The pH of the polishing slurry is 3 or less and theconcentration of the metal-oxidizing agent is within the range of 0.01to 3.0 percent by weight by adjusting the pH of the polishing slurry andthe concentration of the metal-oxidizing agent such that the polishingof tantalums used as the barrier layer conductor is easily advanced in alow pH region and in a low metal-oxidizing agent concentration region(For example, see WO 01/013417).

However, the polishing rate of the barrier layer due to the polishingslurry proposed above is not sufficient as compared with the etchingrate and polishing rate of metal for wiring such as copper and copperalloy. A problem exists in that the state (hereinafter, referred to as“corrosion”) where a foreign matter is occurred on the oxidized surfaceto be polished is easily occurred on the metal surface, particularly onthe metal for wiring such as copper and copper alloy.

The present inventors have found that the high polishing rate of theconductor used for the above barrier layer in a region where the pH is 3or more is obtained for the above proposal. At that time, the presentinventors have also found that as the kind of the oxidized metaldissolving agent used for pH adjustment, an acid in which pKa of a firstdissociable acid group is 3.5 or more and an ammonium salt of the acidare effective.

Since the corrosion operations of the metal for wiring such as copperand copper alloy and the conductor used for the barrier layer arerespectively small in a region wherein the pH is 3 or more in theinvention, the corrosion of the metal wiring portion is not easilyoccurred, and the highly reliable LSI wiring can be formed. In addition,in the region where the pH is 3 or more, the etching rate and polishingrate of the metal of the wiring portion can be sufficiently reduced ascompared with the polishing rate of the barrier layer, and thereby,dishing or thinning is effectively reduced. The concentration of themetal anticorrosive agent to the metal surface can be also reduced.

It is an object of the invention to provide a polishing slurry which canrealize the high polishing rate of the conductor used for the barrierlayer in low polishing particle concentration, and can form theembedding pattern of a highly reliable metal film by suppressing theetching operation of the metal for wiring such as copper and copperalloy by reducing the dishing and thinning of the metal wiring. It isanother object of the invention to provide a polishing method using thepolishing slurry.

SUMMARY OF THE INVENTION

The polishing slurry of the invention relates to the following polishingslurry and polishing method.

(1), That is, the invention relates to a polishing slurry comprising: ametal-oxidizing agent; a metal anticorrosive agent for protecting metalsurface; an oxidized metal dissolving agent; and water, the oxidizedmetal dissolving agent being at least one kind selected from the groupconsisting of an acid in which the negative value of the logarithm ofthe dissociation constant Ka (pKa) of a first dissociable acid group is3.5 or more, an ammonium salt of the acid and an organic acid ester ofthe acid, the pH of the polishing slurry being within the range of 3 to4, the concentration of the metal-oxidizing agent being within the rangeof 0.01 to 3 percent by weight.

(2) The invention relates to the polishing slurry of the (1), whereinthe concentration of the oxidizing agent is within the range of 0.01 to1.5 percent by weight.

(3) The invention relates to the polishing slurry of the (1) or (2),wherein the oxidized metal dissolving agent is an organic acid.

(4) The invention relates to the polishing slurry of the (3), whereinthe oxidized metal dissolving agent is at least one kind selected fromthe group consisting of lactic acid, succinic acid, adipic acid,glutaric acid, benzoic acid, quinaldic acid, butyric acid and valericacid.

(5) The invention relates to the polishing slurry of any one of (1) to(4), wherein the metal anticorrosive agent is at least one kind selectedfrom the group consisting of a compound having a triazole skeleton otherthan benzotriazole, a compound having a pyrimidine skeleton, a compoundhaving an imidazole skeleton, a compound having a guanidine skeleton, acompound having a thiazole skeleton, a compound having a pyrazoleskeleton and benzotriazole.

(6) The invention relates to the polishing slurry of any one of the (1)to (5), wherein the metal-oxidizing agent is at least one kind selectedfrom the group consisting of hydrogen peroxide, ammonium persulfate,ferric nitrate, nitric acid, potassium periodate, hypochlorous acid andozone water.

(7) The invention relates to the polishing slurry of any one of (1) to(6), wherein the polishing slurry contains polishing particles.

(8) The invention relates to the polishing slurry of the (7), thepolishing particles are at least one kind selected from the groupconsisting of silica, alumina, ceria, titania, zirconia and germania.

(9) The invention relates to the polishing slurry of the (7) or (8),wherein the polishing particles are colloidal silica or colloidalalumina having an average particle diameter of 100 nm or less.

(10) The invention relates to the polishing slurry of any one of the (1)to (9), wherein the polishing slurry contains a water-soluble polymercompound.

(11) The invention relates to the polishing slurry of the (10), whereinthe water-soluble polymer compound is at least one kind selected fromthe group consisting of polyacrylic acid and the salt thereof,polymethacrylic acid and the salt thereof, polyacrylamide, polyvinylalcohol, and polyvinylpyrrolidone.

(12) The invention relates to a polishing method comprising: a firstpolishing step of polishing a conductive substance layer of a substratehaving an interlaminar insulating film of which the surface consists ofdented portions and projected portions, a barrier conductor layercoating the interlaminar insulating film along the surface thereof, andthe conductive substance layer with which the dented portions are filledup and coats the barrier conductor layer to expose the barrier conductorlayer of the projected portions; and a second polishing step ofpolishing chemically and mechanically polishing at least the barrierconductor layer and the conductive substance layer of the dentedportions while supplying the polishing slurry of any one of the (1) to(11) to expose the interlaminar insulating film of the projectedportions.

(13) The invention relates to the polishing method of the (12), whereinthe barrier conductor layer prevents the conductive substance fromdiffusing to the interlaminar insulating film, and the conductivesubstance is at least one of copper and a copper alloy.

(14) The invention relates to the polishing method of the (12) or (13),wherein the barrier conductor layer is a single layer made of one kindor a lamination layer made of two kinds or more selected from the groupconsisting of tantalum, tantalum nitride, a tantalum alloy, titanium,titanium nitride, a titanium alloy, tungsten, tungsten nitride and atungsten alloy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the invention will be explained in detail. The polishingslurry of the invention contains the metal-oxidizing agent, the metalanticorrosive agent for protecting metal surface, the oxidized metaldissolving agent and water as a main constituent.

Hereinafter, It will be noted that the composition of the conductor usedfor the barrier layer polished by the polishing slurry is tantalums andthe metal composition for wiring is copper or a copper alloy. However,the polishing slurry is similarly applied for the case that othercomposition usually used, for example, the conductor is titaniumcompounds such as titanium, titanium nitride, a titanium alloy, tungstencompounds such as tungsten, tungsten nitride and a tungsten alloy, andthe case that the metal for wiring is a copper oxide, a copper alloyoxide, tungsten, a tungsten alloy, silver and gold or the like.

Examples of the metal-oxidizing agents in the polishing slurry of theinvention include hydrogen peroxide, ammonium persulfate, ferricnitrate, nitric acid, potassium periodate, hypochlorous acid and ozonewater. Particularly, hydrogen peroxide is preferable. These may be usedalone or combination of more kinds thereof. In the case in which thesubstrate is a silicon substrate containing an element for a integratedcircuit, an oxidizing agent which does not contain nonvolatilecomponents is preferable, so that undesirable pollution caused by alkalimetal, alkali earth metal, halides or the like can be avoided. Ozonewater exhibits rapid change in the composition thereof in a period oftime. Accordingly, hydrogen peroxide is the most preferable as theoxidizing agent. However, if the substrate to be polished is a glasssubstrate which does not contain a semiconductor element, an oxidizingagent containing nonvolatile components may also be acceptable.

The concentration of the metal-oxidizing agent of the invention must bewithin the range of 0.01 to 3 percent by weight in the polishing slurry,more preferably 0.01 to 1.5 percent by weight, and most preferably 0.1to 1.0 percent by weight. When the concentration of the oxidizing agentis less than 0.01 percent by weight, the effect of addition is reduced,and the sufficient polishing rate of tantalums cannot be obtained. Onthe other hand, when the concentration is more than 3 percent by weight,the etching rate of metal such as copper and a copper alloy isincreased, and thereby, the problem of corrosion is easily generated.Also, the polishing rate of tantalums also tends to be reduced.

Generally, when the pH is low, the etching rates of copper film and acopper alloy film are large, and it is difficult to suppress the etchingdue to the metal anticorrosive agent. However, since the concentrationof the metal-oxidizing agent is sufficiently low in the invention, theetching can be suppressed due to the metal anticorrosive agent.

The oxidized metal dissolving agent of the invention is at least onekind selected from the group consisting of an acid in which the negativevalue of the logarithm of the dissociation constant Ka (pKa) of a firstdissociable acid group is 3.5 or more, an ammonium salt of the acid andan organic acid ester of the acid. There are no particular limitationsas long as the oxidized metal dissolving agent is water-soluble.However, organic acids are preferable in view of the etching propertiesof the metal, and examples of the organic acids include lactic acid,succinic acid, adipic acid, glutaric acid, benzoic acid, quinaldic acid,butyric acid, valeric acid, salicylic acid, glyceric acid and pimelicacid. Of these, lactic acid, succinic acid, adipic acid, glutaric acid,benzoic acid, quinaldic acid, butyric acid and valeric acid or the likeare more preferable. The other examples include the ammonium salt ofthese acids and the organic acid ester thereof. It is also effective touse together at least two kinds of acids, ammonium salts or organic acidesters because the etching rate can be effectively suppressed withmaintaining a high, practically acceptable CMP rate.

Preferable examples of the organic acid esters include alkyl ester suchas methyl ester, ethyl ester, 1-propyl ester, 2-propyl ester, 1-butylester, 2-butyl ester, 3-butyl ester, tert-butyl ester. Methyl ester,ethyl ester, 1-propyl ester and 2-propyl ester are more preferable. Thepractical polishing rate of tantalums can be obtained in the regionwhere the pH of the polishing slurry is within the range of 3 to 4 byusing the acid in which the dissociation constant (pKa) of the firstdissociable acid group is 3.5 or more, the ammonium salt of the acid orthe organic acid ester of the acid.

The pH of the polishing slurry of the invention must be within the rangeof 3 to 4. In order to obtain a higher polishing rate of tantalums, thepH is preferably within the range of 3 to 3.75, and the pH is morepreferably within the range of 3 to 3.5. In order to suppress theetching rate of metal such as copper and a copper alloy as compared withthe polishing rate of tantalums, superior characteristic is obtained inthe range where the pH is within the range of 3 to 4 than the rangewhere the pH is less than 3. Though the region where the pH is more than4 is very effective for suppressing the etching operation, the practicalpolishing rate of tantalums is not obtained.

When the pH is set to higher than 4 by the concentration or the like ofthe oxidized metal dissolving agent, the decomposition of the oxidizingagent such as hydrogen peroxide is promoted, and a secondary oxidizedlayer which is harder to be polished than a primary oxidized layer isformed on the film surface of the tantalums. Thereby, the polishing rateis easily reduced.

The pH of the polishing slurry of the invention can be adjusted by theamount of addition of the acid. The pH can be also adjusted by addingalkali components such as ammonia, sodium hydroxide andtetramethylammonium hydroxide (TMAH).

The pH of the polishing slurry of the invention is measured by a pHmeter (for example, Model PH81 (trade name: manufactured by YokogawaElectric Co.)). After a two-point calibration is performed by using astandard buffer solution (the pH of a phthalic acid salt pH buffersolution: 4.21 (25° C.) and the pH of a neutral phosphoric acid salt pHbuffer solution: 6.86 (25° C.)), an electrode is put into the polishingslurry, and a stabilized value after elapse of 2 minutes or more ismeasured.

There are no particular limitations as long as the metal anticorrosiveagent of the invention forms the protective film on the oxidized layerof the surface of the metal film, and prevents the oxidized layer fromsolving in the polishing slurry. At least one kind is preferablyselected from the group consisting of a compound having a triazoleskeleton other than benzotriazole, a compound having a pyrimidineskeleton, a compound having an imidazole skeleton, a compound having aguanidine skeleton, a compound having a thiazole skeleton, a compoundhaving a pyrazole skeleton and benzotriazole (BTA). It is also effectiveto use kinds of two or more together from these.

Examples of the compounds having the triazole skeleton include1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole,benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole,2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole,4-carboxyl(-1H-)benzotriazole, 4-carboxyl(-1H-)benzotriazole methylester, 4-carboxyl(-1H-)benzotriazole buryl ester,4-carboxyl(-1H-)benzotriazole octyl ester, 5-hexyl benzotriazole,[1,2,3-benzotriazolyl-1-methyl][1,2,4-triazolyl-1-methyl][2-ethylhexyl]amine,tolyltriazole, naphthotriazole, bis[(1-benzotriazolyl)methyl]phosphonicacid, 3-aminotriazole and 5-methyl benzotriazole. Of these, in view ofthe polishing rate and the etching rate, 1,2,3-triazole, 1,2,4-triazole,3-amino-1H-1,2,4-triazole, 4-amino-4H-1,2,4-triazole, benzotriazole,1-hydroxybenzotriazole and 5-methybenzotriazole are more preferable.These may be used alone or combination of more kinds thereof.

Examples of the compounds having the imidazole skeleton include2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole,2-propylimidazole, 2-butylimidazole, 4-methylimidazole,2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole and2-aminoimidazole. These may be used alone or combination of more kindsthereof.

Examples of the compounds having the pyrimidine skeleton includepyrimidine, 1,2,4-triazolo[1,5-a]pyrimidine,1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine,1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine,2,4,5,6-tetraaminopyrimidinesulfate, 2,4,5-trihydroxypyrimidine,2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine,2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine,2,4-diamino-6-hydroxylpyrimidine, 2,4-diaminopyrimidine,2-acetamidepyrimidine, 2-aminopyrimidine,2-methyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine,2-methylsulfanilyl-5,7-diphenyl(1,2,4)triazolo(1,5-a)pyrimidine,2-methylsulfanilyl-5,7-diphenyl-4,7-dihydro-(1,2,4)triazolo (1,5-a)pyrimidine and 4-aminopyrazolo[3,4-d]pyrimidine. Particularly, in viewof the polishing rate and the etching rate,4-aminopyrazolo[3,4-d]pyrimidine, 1,2,4-triazolo(1,5-a)pyrimidine,2-methyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine,2-methylsulfanilyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine arepreferable. These may be used alone or combination of more kindsthereof.

Examples of the compounds having the guanidine skeleton include1,3-diphenyl guanidine and 1-methyl-3-nitroguanidine. Examples of thecompounds having the thiazole skeleton include 2-mercaptobenzothiazole.These may be used alone or combination of more kinds thereof.

The polishing slurry of the invention may contain polishing particles,and the polishing rate of tantalums can be improved by containing thepolishing particles. A silicon dioxide film is used as the insulatingfilm layer of copper or a copper alloy wiring such as LSI, in this case,when the silicon dioxide film is polished by using the polishing slurryof the invention after polishing the tantalums as the barrier layer, thepolishing slurry preferably contains the polishing particles.

As the polishing particles used in the invention, inorganic polishingparticles such as silica, alumina, zirconia, ceria, titania, germaniaand silicon carbide, and organic polishing particles such aspolystyrene, polyacryl and polyvinyl chloride may be used. At least onekind selected from silica, alumina, ceria, titania, zirconia andgermania is preferable. Colloidal silica and colloidal alumina whichhave excellent dispersion stability in the polishing slurry, have thefew number of polishing cracks (scratches) generated by CMP and have anaverage particle diameter of 150 nm or less are preferable. Herein, theaverage particle diameter of 100 nm or less which increases thepolishing rate of the barrier layer is more preferable, and mostpreferably 70 nm or less. It is noted that the colloidal silica ismanufactured by hydrolysis of silicon alcoxide or ion exchange of sodiumsilicate and the colloidal alumina is manufactured by hydrolysis ofaluminium nitrate.

The particle diameter of the polishing particles of the invention ismeasured by an optical diffraction scattering particle size distributionmeter (for example, trade name: COULTER N4SD, manufactured by COULTERElectronics). The measurement conditions of the particle sizedistribution meter (COULTER N4SD) are the following. The measurementtemperature is set to 20° C., and the solvent refractive index is set to1.333 (water). The particle refractive index is set to Unknown (set),and the solvent viscosity is set to 1.005 cP (water). The Run Time isset to 200 sec, and the laser incidence angle is set to 90 degrees. Whenthe Intensity (corresponding to scattering intensity and turbidity) ishigher than 4E+05, the polishing slurry is diluted by water and measuredsuch that the Intensity is within the range of 5E+04 to 4E+05.

The polishing slurry of the invention may contain a water-solublepolymer compound. As the water-soluble polymer compound used in theinvention, at least one kind is suitably selected from the groupconsisting of a polymer which contains a monomer having a carboxyl groupsuch as polyacrylic acid, polyacrylic acid ammonium salt, polyacrylicacid sodium salt, polymethacrylic acid, polymethacrylic acid ammoniumsalt, polymethacrylic acid sodium salt and polyacrylamide as the basicconstitutional unit; and a polymer which contains a monomer having avinyl group such as polyvinyl alcohol and polyvinylpyrrolidone as thebasic constitutional unit. Particularly, the water-soluble polymercompound is preferably at least one kind selected from the groupconsisting of polyacrylic acid and the salt thereof, polymethacrylicacid and the salt thereof, polyacrylamide, polyvinyl alcohol andpolyvinylpyrrolidone.

In the case in which the substrate is a silicon substrate for asemiconductor integrated circuit, a water-soluble polymer is preferablyan acid or an ammonium salt thereof, such that undesirable pollutioncaused by alkali metal, alkali earth metal, halides or the like can beavoided. However, when the substrate is a glass substrate or the like,such restriction as described above is unnecessary.

By adding these water-soluble polymer compounds, the dishingcharacteristic can be improved by the etching restraining effect due tothe metal anticorrosive agent.

The content the metal anticorrosive agent used in the invention ispreferably within the range of 0.001 to 5.0 percent by weight based onthe total weight of the polishing slurry, more preferably 0.01 to 1.0percent by weight, and particularly preferably 0.01 to 0.5 percent byweight. When the content is less than 0.001 percent by weight, it tendsto be difficult to suppress the etching of the metal. Even when thecontent is more than 5 percent by weight, there is no difference in theeffect, and a problem in that the metal anticorrosive agent is easilyre-eluted may be occurred.

The content of the oxidized metal dissolving agent used in the inventionis preferably within the range of 0.001 to 10.0 percent by weight basedon the total weight of the polishing slurry, more preferably 0.01 to 5.0percent by weight, and particularly preferably 0.01 to 2.0 percent byweight. When the content is less than 0.001 percent by weight, it isdifficult to set the polishing slurry to a predetermined pH value. Whenthe pH is high, the polishing rate tends to be reduced. When the contentis more than 10.0 percent by weight, the etching rate is increased whilethe pH is reduced, and a problem of the corrosion of the metal wiringtends to be occurred.

The content of water may be the remainder, and there are no particularlimitations as long as water is contained. The water-soluble polymercompound and the polishing particles are arbitrary ingredients asdescribed above.

When the water-soluble polymer compound is blended, the content of thewater-soluble polymer compound is preferably within the range of 0.001to 0.5 percent by weight based on the total weight of the polishingslurry, and more preferably 0.01 to 0.2 percent by weight. When thecontent is less than 0.001 percent by weight, the combined use effectwith the metal anticorrosive agent tends not to be exhibited for thesuppression of etching. When the content is more than 0.5 percent byweight, the polishing rate due to CMP tends to be reduced.

The weight average molecular weight of the water-soluble polymercompound is preferably 500 or more. Though the maximum of the weightaverage molecular weight is not particularly specified, the weightaverage molecular weight is preferably 5 million or less are preferredin view of the solubility. When the weight average molecular weight isless than 500, the polishing rate of tantalums tends to be easilyreduced. In respect of the etching of copper and a copper alloy, acopolymer obtained by reacting with a polymer compound of which theweight average molecular weight is small having a hydrophobic group iseffective.

When the polishing particles are blended, the concentration of thepolishing particles is preferably within the range of 0.01 to 20.0percent by weight based on the total weight of the polishing slurry,more preferably 0.05 to 15.0 percent by weight, and most preferably 0.1to 8.0 percent by weight. When the concentration of the polishingparticles is less than 0.01 percent by weight, the polishing particlesadding effect is lost. When the concentration of the polishing particlesis more than 20.0 percent by weight, not only the polishing particlesare easily flocked, but also there is no difference in the polishingrate.

In the polishing slurry of the invention, when the concentration of theoxidizing agent based on the total weight of the polishing slurry isabout 0.15 percent by weight, the polishing rate of tantalums becomesmaximized. A primary oxidized layer which is polished easily andmechanically is formed on the film surface of tantalums by the oxidizingagent, and the high polishing rate is obtained.

On the other hand, when the concentration of the oxidizing agent used inthe invention is more than 3 percent by weight, the etching rate ofmetal such as copper and a copper alloy is increased, and thereby,dishing or the like is easily generated. In addition, since thesecondary oxidized layer which is harder to be polished than the primaryoxidized layer is formed on the film surface of tantalums, the polishingrate is reduced. When the concentration of the oxidizing agent is lessthan 0.01 percent by weight, the oxidized layer is not sufficientlyformed. Thereby, the polishing rate is reduced, and the exfoliation orthe like of the film of tantalums may be generated.

The polishing slurry of the invention may contain suitably dispersingagents such as a surface-active agent; pH buffers; colorants such asdyes such as Victoria pure blue, pigments such as phthalocyanine green;and organic solvents such as methanol and ethylene glycol if neededother than the materials described above.

The polishing slurry of the invention can be applied, for example to theformation of a metal wiring layer in a semiconductor device, and can beused for chemical mechanical polishing (CMP) of the conductive substancelayer, the conductor layer used as the barrier layer and theinterlaminar insulating film.

That is, the polishing method of the invention comprises: a firstpolishing step of polishing a conductive substance layer of a substratehaving an interlaminar insulating film of which the surface consists ofdented portions and projected portions, a barrier conductor layer(barrier layer) coating the interlaminar insulating film along thesurface thereof, and the conductive substance layer with which thedented portions are filled up and coats the barrier layer to expose thebarrier layer of the projected portions; and a second polishing step ofpolishing chemically and mechanically polishing at least the barrierlayer and the conductive substance layer of the dented portions whilesupplying the polishing slurry of the invention to expose theinterlaminar insulating film of the projected portions.

Examples of the conductive substances include substances in which themetal is a main ingredient such as copper, a copper alloy, a copperoxide, an oxide of a copper alloy, tungsten, a tungsten alloy, silverand gold. The conductive substance in which copper is a main ingredientsuch as copper, a copper alloy, a copper oxide and an oxide of a copperalloy is preferable, and more preferably, at least one of copper and acopper alloy. As the conductive substance layer, a film obtained byforming the substance by the known spatter method and plating method canbe used.

The barrier layer applied for the invention is preferably for the aboveconductive substance, particularly the barrier layer for copper and acopper alloy. The barrier layer is formed in order to prevent theconductive substance from diffusing into an insulating film and enhancethe adhesion between the insulating film and the conductive substance.Examples of the composition of the conductor forming the barrier layerinclude tantalum compounds such as tantalum, tantalum nitride and atantalum alloy, titanium compounds such as titanium, titanium nitrideand a titanium alloy, and tungsten compounds such as tungsten, tungstennitride and a tungsten alloy. The composition of the conductor ispreferably selected from tantalum, tantalum nitride, a tantalum alloy,titanium, titanium nitride, a titanium alloy, tungsten, tungsten nitrideand a tungsten alloy. The barrier layer may have a single layerstructure consisting of one kind or a lamination layer structureconsisting of two kinds or more.

Examples of the interlaminar insulating films include a silicone basedcoating film and an organic polymer film. Examples of the silicone basedcoating films include silicon dioxide, fluoro silicate glass,organosilicate glass obtained by using trimethylsilane anddimethoxydimethylsilane as a starting material, silicon oxynitride,silica based coating films such as hydrogenated silsesquioxane, siliconcarbide and silicon nitride. Examples of the organic polymer filmsinclude all aromatic low dielectric constant interlaminar insulatingfilm. Particularly, organosilicate glass is preferable. These films areformed by a CVD method, a spin coat method, a dip coat method or a spraymethod.

In the polishing method of the invention, as a polishing machine, agenerally-used polishing machine which includes a holder for holding asubstrate having the surface to be polished and a polishing platenhaving a polishing pad stacked thereon and a motor or the like mountedthereon whose speed of rotation is adjustable can be used when thesubstrate is polished by the polishing pad.

The material of the polishing pad stacked on the polishing platen is notparticularly restricted, and common nonwoven fabric, foamedpolyurethane, porous fluororesin and the like can be used as thepolishing pad. It is preferable that a groove is formed on the polishingpad such that the polishing slurry is collected.

Though there is no particular restriction on the polishing condition,the rotational speed of the platen is preferably kept low (no higherthan 200 rpm) such that the substrate does not come off. The polishingpressure (processing load) at which the surface to be polished, of thesubstrate, is pressed against the polishing pad is preferably 1 to 100kPa, and in order to achieve the homogeneity of the polishing rate onthe surface to be polished and pattern-flatness in the satisfactorymanner, is more preferably 5 to 50 kPa. The polishing slurry of theinvention is continually supplied in the space between the polishing padand the surface to be polished by a pump or the like during polishing.Though there is no restriction on the amount, to be supplied, of thepolishing slurry, it is preferable that the surface of the polishing padis constantly covered with the polishing slurry.

Particularly, a surface to be polished, of a substrate, can be polishedby moving a polishing pad relative to the substrate in the state inwhich the surface to be polished of the substrate is pressed against apolishing pad, while the polishing slurry is supplied onto the polishingpad stacked on the polishing platen. In order to move the polishing padrelative to the substrate, the substrate may be polished by the rotationand fluctuation of the holder in addition to the rotation of thepolishing platen. There can be mentioned a polishing method for rotatingepicyclically a polishing platen and a polishing method for movingrectilinearly a belt-like polishing pad in one direction of thelongitudinal direction. The holder may be in the fixing, rotating orfluctuating state. These polishing methods can be suitably selected bythe surface to be polished or the polishing machine as long as thepolishing pad is moved relative to the substrate.

When the polishing of the substrate is completed, the substrate isthoroughly washed with flowing water, water drops attached on thesubstrate were removed by using spin dry or the like, and dried.

Hereinafter, the embodiment of the polishing method of the inventionwill be explained along with the formation of the wiring layer in thesemiconductor device.

First, an interlaminar insulating film made of silicon dioxide or thelike are laminated on a silicon substrate. A specified pattern of dentedportions (the exposed portion of the substrate) is then formed on thesurface of the interlaminar insulating film by the known means such asthe formation of a resist layer and etching, and thereby theinterlaminar insulating film consisting of the projected portions andthe dented portions is formed. The barrier layer such as tantalumscoating the interlaminar insulating film along the unevenness of thesurface thereof on this interlaminar insulating film is formed by avapor deposition method or a CVD method or the like. The conductivesubstance layer such as copper coating the barrier layer such that thedented portions are filled up with the conductive substance is formed bythe vapor deposition method, the plating method or the CVD method or thelike. It is preferable that the forming thickness of the interlaminarinsulating film, the barrier layer and the conductive substance,generally, is about within the range of 0.01 to 2,0 μm, 1 to 100 nm and0.01 to 2.5 μm.

Next, the conductive substance layer formed on the surface of thesemiconductor substrate is polished by CMP using the polishing slurryfor the conductive substance of which the polishing rate ratio of theconductive substance/the barrier layer is sufficiently large, forexample (first polishing process). Thereby, the barrier layer of theprojected portions formed on the substrate is exposed to the surface,and a desired wiring pattern is obtained by leaving the conductivesubstance layer in the dented portions. The obtained pattern surface canbe polished as the surface to be polished for the second polishingprocess in the polishing method using the polishing slurry of theinvention.

In the second polishing process, the polishing slurry of the inventionwhich can polish the conductive substance, the barrier layer and theinterlaminar insulating film is used, and at least the exposed barrierlayer and the conductive substance formed in the dented portions arepolished by chemical machical polishing. The polishing is completed whena desired pattern is obtained in which the section of the barrier layeris exposed to the boundary between the dented portion and the projectedportion, the whole of interlaminar insulating film under the barrierlayer of the projected portions is exposed, and the conductive substancelayer as the wiring layer at the dented portions is left. In order tosecure more superior flatness at the time of the polish completion, apart of the interlaminar insulating film of the projected portions maybe further polished as over-polishing (when time until a desired patterncan be obtained by the second polishing process is 100 seconds, 50%over-polishing means polishing executed by adding the polishing for 50seconds to the polishing for 100 seconds).

Thus, an interlaminar insulating film and a second metal wiring arefurther formed on the metal wiring such as copper formed as describedabove. After an interlaminar insulating film is formed between thewirings and on the wiring again, similarly, the entire surface of thesemiconductor substrate is polished, and is formed as a smooth plane.The semiconductor device having the desired number of wiring layers canbe manufactured by repeating the process at a predetermined number.

EXAMPLES

The present invention will be explained further in detail by thefollowing examples hereinafter. It should be noted that the presentinvention is not restricted by any means to these examples.

Examples 1 to 5, Comparative Examples 1 to 3

[Method for Producing Polishing Slurry]

3.0 percent by weight of colloidal silica polishing particles having anaverage particle diameter of 70 nm, 1.0 percent by weight of hydrogenperoxide solution (a guaranteed reagent, an aqueous solution of 30percent by weight), BTA (benzotriazole) as the metal anticorrosive agentand oxidized metal dissolving agent shown in Table 1, in theconcentrations (unit: percent by weight) shown in Table 1, and purewater were blended such that the total amount became 100 percent byweight based on the total weight of the polishing slurry. An ammoniawater (25%) was added and adjusted such that the pH of the resultantsolution was set to pH specified in Table 1, and the polishing slurryused in Examples 1 to 5 and Comparative Examples 1 to 3 was produced.

Polishing substrates were chemically and mechanically polished onfollowing conditions using each polishing slurry produced above.

[Polishing Substrate]

Substrate (A): Silicon substrate having no pattern and having a diameterof 5 inch (12.5 cm)

(a) Silicon substrate on which a tantalum film having a thickness of 200nm was formed (Film structure: Silicon substrate/Silicon dioxide havinga film thickness 300 nm/Tantalum film having a film thickness of 200 nm)

(b) Silicon substrate on which a tantalum nitride film having athickness of 100 nm was formed (Film structure: Siliconsubstrate/Silicon dioxide having a film thickness of 300 nm/Tantalumnitride film having a film thickness of 100 nm)

(c) Silicon substrate on which a silicon dioxide film having a thicknessof 1 μm was formed (Film structure: Silicon substrate/Silicon dioxidefilm having a film thickness of 1 μm)

(d) Silicon substrate on which a copper film having a thickness of 1.2μm was formed (Film structure: Silicon substrate/Silicon dioxide havinga film thickness of 300 nm/Barrier layer: Tantalum nitride having a filmthickness of 25 nm/Copper having a film thickness of 1.2 μm)

Substrate (B): Silicon substrate having a pattern and having a diameterof 5 inch (12.5 cm) (Silicon substrate on which grooves having a depthof 0.5 μm were formed/Silicon dioxide having a film thickness of 300nm/Barrier layer: Tantalum nitride having a film thickness of 50nm/Copper having a film thickness of 1.2 μm)

The above substrate (B) was produced by the following method. Grooveshaving a wiring density of 50%, wiring width of 0.35 to 100 μm and adepth of 0.5 μm were formed on a silicon substrate, and a silicondioxide film having a thickness of 300 nm was formed by the known plasmaCVD method. A tantalum nitride film having a thickness of 50 nm as thebarrier layer was formed by the known spatter method. Similarly, acopper film of 1.2 μm was formed by the spatter method, and theresultant substrate was subjected to the known heat treatment.

As the specific resistance values of the above copper and conductor usedfor evaluation of the polishing rate and etching rate, a copper film of1.83 μΩ cm, a tantalum nitride film of 263 μΩ cm and a tantalum film of184 μΩ cm were used.

[Polishing Condition]

Supply of polishing slurry: 50 cc/minute

Polishing machine: deadweight load type polishing machine for experiment(the diameter of a polishing platen: φ40 cm)

Polishing pad: Foamed polyurethane resin (IC1000, manufactured by RodelInc.)

Polishing pressure: 14 kPa

Relative speed of the substrate with respect to the polishing platen: 36m/min

Rotating rate of a polishing platen: 60 rpm

A resistance meter Model RT-80 (trade name, manufactured by NapsonCompany) was used for measuring the sheet resistance value forcalculating the film thickness before and behind CMP and etchingprocess.

[Evaluation Item of Polishing Slurry]

(1) Etching rate: The etching rate was obtained from the difference infilm thickness of the copper layer before or after the immersion of asubstrate having a copper film and no pattern in the polishing slurriesof Examples and Comparative Examples which were being stirred (roomtemperature of 25° C., the stirring rate of 100 rpm), which differencein film thickness being converted from the electric resistance.

(2) Polishing rate due to CMP: The difference in film thickness beforeor after the above substrate (A) (Substrate having no pattern: Siliconsubstrate having a copper film, tantalum nitride, a tantalum film or asilicon dioxide film) was chemically and mechanically polished for 1minute was obtained by being converted from the electric resistance.

(3) Magnitude of dishing: Copper was chemically and mechanicallypolished by using a polishing slurry (trade name: HS·4000, manufacturedby Hitachi Chemical Co., Ltd.) until the barrier layer made of tantalumnitride was exposed on the entire surface of the above substrate (B)(first polishing process). The polishing slurry has a sufficiently largepolishing rate ratio of copper to tantalum nitride, and is a polishingslurry for copper which contains no polishing particle.

The magnitude of dishing measured at a 100/100 μm pattern portion was 50nm in the state that the barrier layer was exposed on an insulated filmportion after the above first polishing process, and the magnitude ofthinning measured at a 4.5/0.5 μm pattern portion was 20 nm. Then, thesurface was polished by the polishing slurries of Examples andComparative Examples until tantalum nitride on the insulated filmportion was lost (second polishing process). The substrate was polishedfor the time obtained by adding 1 minute to the polishing time oftantalum nitride of 50 nm in the polishing rate conversion evaluated byCMP of a tantalum nitride substrate having no pattern.

The reduction in film thickness (magnitude of dishing) of the wiringmetal portion to the insulated film portion was then obtained, by usinga surface profilometer, from the surface configuration of thestripe-like pattern portion in which the wiring metal portions of 100 μmwidth and the insulating film portions of 100 μm width were alternatelyarranged.

(4) Magnitude of thinning: The surface configuration of the stripe-likepattern portion having a total width of 2.5 mm in which wiring metalportions of 4.5 μm width and insulating film portions of 0.5 μm widtharranged alternately formed on the substrate in which the above (3)magnitude of dishing was evaluated was measured by using the surfaceprofilometer. The reduction in film thickness of the insulated filmportion near the center of the pattern to the insulating film fieldportion around the stripe-like pattern was then obtained.

(5) Corrosion: The surface to be polished after evaluating the above (4)magnitude of thinning was observed with 1000 magnifications using amicroscope (trade name: AL-2000, manufactured by Olympus Optical Co.,Ltd.), and presence/absence of generation of foreign matterlikeprojections was evaluated.

The evaluation results (the polishing rate of the various films by CMP,the etching rate of copper, the magnitude of dishing, the magnitude ofthinning and presence/absence of corrosion) in Examples 1 to 5 andComparative Examples 1 to 3 were shown in Table 1.

TABLE 1 oxidized metal Example dissolving CMP polishing rate(nm/min) No.agent BTA pH Tantalum Silicon unit wt % wt % — Cupper Tantalum nitridedioxide Example 1 succinic acid 0.6 0.15 3.13 16.0 45.0 63.5 15.5 2lactic acid 0.05 0.15 3.05 8.0 24.3 38.0 15.0 3 adipic acid 0.6 0.103.23 12.0 35.5 53.5 16.0 4 glutaric acid 0.6 0.10 3.18 14.0 39.5 56.514.8 5 glutaric acid 0.6 0.15 3.55 12.5 29.5 48.5 15.0 ComparativeExample 1 oxalic acid 0.15 0.2 2.40 33.5 31.5 42.5 15.2 2 malic acid 0.50.2 3.70 17.0 15.0 29.8 14.8 3 succinic acid 0.6 0.15 4.10 3.5 10.0 19.514.5 oxidized Corrosion metal Cupper Magnitude Magnitude of Exampledissolving etching of of Cupper No. agent rate dishing thinning wiringunit wt % nm/min nm nm — Example 1 succinic acid 0.6 0.3 20 30 absence 2lactic acid 0.05 0.6 35 30 absence 3 adipic acid 0.6 0.1 25 25 absence 4glutaric acid 0.6 0.2 25 25 absence 5 glutaric acid 0.6 0.0 40 30absence Comparative Example 1 oxalic acid 0.15 30.0 80 60 presence 2malic acid 0.5 0.2 65 40 absence 3 succinic acid 0.6 0.1 55 35 absence

An organic acid of which the pKa was small was used in the ComparativeExample 1. Since the pH of the polishing slurry was low, the polishingrate of copper was large, and the flatness characteristic such asdishing and thinning was inferior. In addition, when the substratehaving the pattern was polished, corrosion was found at the copperwiring portion. Since an organic acid of which the pKa was comparativelysmall was used and the pH was adjusted to pKa or more in the ComparativeExample 2, the polishing rate of the tantalum system conductor was smalland the flatness characteristic was also inferior. Though an acid ofwhich the pKa was 3.5 or more was used in the Comparative Example 3,since the pH was adjusted to 4 or more, the polishing rate of thetantalum system conductor was small and flatness efficiency was alsoinferior.

On the other hand, in Examples 1 to 5, the high polishing rate,excellent dishing and thinning characteristics of the tantalum systemconductor were obtained.

INDUSTRIAL APPLICABILITY

According to the invention, in the wiring-formation process of thesemiconductor device, the high polishing rate of the conductor used forthe barrier layer can be realized by the polishing slurry having lowpolishing particle concentration and low metal anticorrosive agentconcentration. The occurrence of the dishing and thinning of the metalwiring is reduced by suppressing the etching of the metal for wiring,and highly reliable embedding wiring pattern of the metal film can beformed. According to the polishing slurry and polishing method of theinvention, the high-reliability semiconductor device and apparatus whichare excellent in miniaturization, thin film, dimensional accuracy andelectrical characteristic can be suitably manufactured.

1. A polishing method for polishing a material comprising: a substrate,an interlaminar insulating film on said substrate, wherein a surface ofsaid interlaminar insulating film comprises dented portions andprojected portions, a barrier conductor layer coated along said surfaceof said interlaminar insulating film, wherein said barrier conductorlayer comprises dented portions and projected portions corresponding tothe dented portions and projected portions of said interlaminarinsulating film, a conductive substance layer coated on said barrierconductor layer, wherein said conductive substance layer fills thedented portions of said barrier conductor layer and covers the projectedportions of said barrier conductor layer, said method comprising: afirst polishing step of polishing said conductive substance layer toexpose projected portions of said barrier conductor layer; and a secondpolishing step of chemically polishing and mechanically polishing atleast the exposed projected portions of said barrier conductor layer andthe conductive substance layer while supplying a polishing slurry toexpose the interlaminar insulating film at locations corresponding tothe projected portions of said interlaminar insulating film, withconductive substance layer at the dented portions of said barrierconductor layer remaining; said polishing slurry comprising: ametal-oxidizing agent; a metal anticorrosive agent; an oxidized metaldissolving agent; and water, wherein the oxidized metal dissolving agentis at least one kind selected from the group consisting of an acid inwhich the negative value of the logarithm of the dissociation constantKa (pKa) of a first dissociable acid group is 3.5 or more, an ammoniumsalt of the acid and an organic acid ester of the acid, the pH of thepolishing slurry is within the range of 3 to 4, and the concentration ofthe metal-oxidizing agent is within the range of 0.01 to 3 percent beweight.
 2. The polishing method of claim 1, wherein the barrierconductor layer prevents the conductive substance from diffusing to theinterlaminar insulating film, and the conductive substance is at leastone of copper and a copper alloy.
 3. The polishing method of claim 1,wherein the barrier conductor layer is a single layer made of one kindor a lamination layer made of two kinds or more selected from the groupconsisting of tantalum, tantalum nitride, a tantalum alloy, titanium,titanium nitride, a titanium alloy, tungsten, tungsten nitride and atungsten alloy.
 4. The polishing method of claim 1, wherein theconcentration of the oxidizing agent is within the range of 0.01 to 1.5percent by weight.
 5. The polishing method of claim 1, wherein theoxidized metal dissolving agent is an organic acid.
 6. The polishingmethod of claim 1, wherein said dented portions and projected portionsare formed in a specified pattern.
 7. The polishing method of claim 6,wherein said dented portions are formed on the surface of theinterlaminar insulating film by forming a resist layer and etching.
 8. Apolishing method of polishing a material comprising: a substrate, aninterlaminar insulating film on said substrate, wherein a surface ofsaid interlaminar insulating film comprises dented portions andprojected portions, a barrier conductor layer coated along said surfaceof said interlaminar insulating film, wherein said barrier conductorlayer comprises dented portions and projected portions corresponding tothe dented portions and projected portions of said interlaminarinsulating film, a conductive substance layer coated on said barrierconductor layer, wherein said conductive substance layer fills thedented portions of said barrier conductor layer and covers the projectedportions of said barrier conductor layer, said method comprising: afirst polishing step of polishing said conductive substance layer toexpose projected portions of said barrier conductor layer; and a secondpolishing step of chemically polishing and mechanically polishing atleast the exposed projected portions of said barrier conductor layer andthe conductive substance layer while supplying a polishing slurry toexpose the interlaminar insulating film at locations corresponding tothe projected portions of said interlaminar insulating film, withconductive substance layer at the dented portions of said barrierconductor layer remaining, said polishing slurry comprising: ametal-oxidizing agent; a metal anticorrosive agent; an oxidized metaldissolving agent; and water, wherein the oxidized metal dissolving agentis at least one kind selected from the group consisting of an acid inwhich the negative value of the logarithm of the dissociation constantKa (pKa) of a first dissociable acid group is 3.5 or more, an ammoniumsalt of the acid and an organic acid ester of the acid, the pH of thepolishing slurry is within the range of 3 to 4 and the concentration ofthe metal-oxidizing agent is within the range of 0.01 to 3 percent byweight, and wherein the barrier layer is selected from the groupconsisting of tantalum compounds and titanium compounds.
 9. Thepolishing slurry of claim 8, wherein the barrier layer is selected fromthe group consisting of tantalum, tantalum nitride, tantalum alloys,titanium, titanium nitride and titanium alloys.
 10. A polishing methodfor polishing a material comprising: a substrate, an interlaminarinsulating film on said substrate, wherein a surface of saidinterlaminar insulating film comprises dented portions and projectedportions, a barrier conductor layer coated along said surface of saidinterlaminar insulating film wherein said barrier conductor layercomprises dented potions and projected portions corresponding to thedented portions and projected portions of said interlaminar insulatingfilm, a conductive substance layer coated on said barrier conductorlayer, wherein said conductive substance layer fills the dented portionsof said barrier conductor layer and covers the projected portions ofsaid barrier conductor layer, said method comprising: a first polishingstep of polishing said conductive substance layer to expose projectedportions of said barrier conductor layer; and a second polishing step ofchemically polishing and mechanically polishing at least the exposedprojected portions of said barrier conductor layer and the conductivesubstance layer while supplying a polishing slurry to expose theinterlaminar insulating film at locations corresponding to the projectedportions of said interlaminar insulating film, with conductive substancelayer at the dented portions of said barrier conductor layer remaining,said polishing slurry comprising: a metal polishing slurry comprising: ametal-oxidizing agent: a metal anticorrosive agent; an oxidized metaldissolving agent; and water, wherein the oxidized metal dissolving agentis at least one kind selected from the group consisting of an acid inwhich the negative value of the logarithm of the dissociation constantKa (pKa) of a first dissociable acid group is 3.5 or more an ammoniumsalt of the acid and an organic acid ester of the acid, the pH of thepolishing slurry is within the range of 3 to 3.75, and the concentrationof the metal-oxidizing agent is within the range of 0.01 to 3 percent byweight.
 11. A polishing method of polishing a material comprising: asubstrate, an interlaminar insulating film on said substrate, wherein asurface of said interlaminar insulating film comprises dented portionsand projected portions, a barrier conductor layer coated along saidsurface of said interlaminar insulating film, wherein said barrierconductor layer comprises dented portions and projected portionscorresponding to the dented portions and projected portions of saidinterlaminar insulating film, a conductive substance layer coated onsaid barrier conductor layer, wherein said conductive substance layerfills the dented portions of said barrier conductor layer and covers theprojected portions of said barrier conductor layer, said methodcomprising: a first polishing step of polishing said conductivesubstance layer to expose projected portions of said barrier conductorlayer; and a second polishing step of chemically polishing andmechanically polishing at least the exposed projected portions of saidbarrier conductor layer and the conductive substance layer whilesupplying a polishing slurry to expose the interlaminar insulating filmat locations corresponding to the projected portions of saidinterlaminar insulating film, with conductive substance layer at thedented portions of said barrier conductor layer remaining, saidpolishing slurry comprising: a metal-oxidizing agent, a metalanticorrosive agent, an oxidized metal dissolving agent, and water,wherein the oxidized metal dissolving agent is at least one kindselected from the group consisting of an acid in which the negativevalue of the logarithm of the dissociation constant Ka (pKa) of a firstdissociable acid group is 3.5 or more, an ammonium salt of the acid andan organic acid ester of the acid, the pH of the polishing slurry iswithin the range of 3 to 4, and the concentration of the metal-oxidizingagent is within the range of 0.01 to 3 percent by weight, and whereinthe polishing slurry contains polishing particles having an averageparticle diameter of 100 nm or less.